Security grilles are used to meet special requirements of ventilation systems of penal institutions and prisoner detention cells. The grilles must not be readily removable in order to address concerns regarding escape, the concealment of weapons, drugs or other prohibited contraband. The grilles must be difficult for a person wishing to commit suicide by hanging to attach a line.
A number of factors have lead to a major renovation program relating to the ventilation systems in our penal institutions. One factor is a desire on the part of the penal institutions to prevent the concealment of weapons and drugs. Another factor is a desire on the part of the institutions to eliminate suicide death by hanging. Yet another factor are studies regarding the need for an increased number of changes in the air of the cell per hour in order to maintain the mental and physical health of inmates. Some penal institutions which were built with ventilation systems capable of handling three to six air changes per hour, are faced with the task of upgrading to as many as 20 air changes per hour to meet the requirements of State laws regarding prisoners rights.
In order to change the air in a prison cell twenty times every hour, a larger grille is required than would be required to change the air in a prison cell only six times per hour. The greater security provided by a grille, the less area is available to provide for air flow. A lower security grille might have 50% or more of its surface area available for air flow, whereas a higher security grille might only have 25% to 35% of its surface area available for air flow. In order to accommodate greater security, more frequent air changes, or both; grilles with substantially larger surface area are being installed. This requires that ducts be enlarged through concrete walls at considerable cost. Sometimes the enlarging of the ducts is practically impossible due to a heavy metal flange bordering the air duct.